AN1965 Freescale Semiconductor / Motorola, AN1965 Datasheet - Page 4

• Manufacturer Part Number: AN1965
• Description: Design of Indirect Power Using the 56F800/E
• Manufacturer: Freescale Semiconductor / Motorola

Power Factor Correction (PFC) Theory
4
~115V 60Hz
~230V 50Hz
The Control Process
The PFC performs correction of the input current waveform. The standard power supply with a
rectifier and large electrolytic capacitor has an excessive peak of input current. This peak appears
when the voltage from the rectifier is greater than the voltage on the capacitor; see
Zero crossing
detection
Input Frequency
Zero-crossing
Measurement
Generation
Milestone
Detection
Freescale Semiconductor, Inc.
For More Information On This Product,
Pulse Width
Modulation
Frequency
Figure 3-1. System Concept
Indirect Power Factor Correction
Base
External Pulse Width Modulator
Go to: www.freescale.com
56F800/E
L
T
&
Output
Inhibit
D
D
C
Output Voltage
Output Voltage
Measurement
Measurement
Calculation
Reference
= 385V
Voltage
Figure 3-2.
Load